JP4208271B2 - Grid-controlled rotating anode X-ray tube - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an X-ray tube apparatus that generates X-rays for providing effective image information by medical diagnosis, and an X-ray image imaging apparatus using the X-ray tube apparatus.
[0002]
[Prior art]
An X-ray image pickup device is useful for examining the inside of a human body or an object, and converts an X-ray transmission density distribution or an X-ray image irradiated on the human body or an object into an electrical image signal, for example, a monitor device. In addition, an X-ray transmission density distribution or an X-ray image is displayed in real time.
[0003]
An X-ray imaging apparatus includes an X-ray generator that generates X-rays, an X-ray detector that detects X-rays from an object to be imaged, that is, an X-ray generator that has passed through a human body, and an X-ray detector. And a monitor device that can monitor the image signal converted from the X-ray in real time.
[0004]
X-rays emitted from the X-ray generator pass through the human body and enter the X-ray detector as a transmission density distribution or an X-ray image. The transmission density distribution or the X-ray image is converted into an electric image signal by an X-ray detector, subjected to predetermined image processing by an image processing device, and then output to a monitor device.
[0005]
By the way, a method for reducing exposure to a patient in catheter treatment in order to reduce the influence on the human body as the X-ray dose irradiated to the subject to be examined, that is, the specimen, is smaller, and to enable imaging at an optimal timing. X-ray irradiation during the readout time of the CCD sensor by controlling the X-ray grid emitted from the X-ray source and converting the X-ray image obtained by the X-ray image intensifier tube into an electrical signal by the CCD sensor A pulse fluoroscopy method has been realized in which the pause is repeated at high speed.
[0006]
[Problems to be solved by the invention]
However, in order to obtain a high-contrast image, it is necessary to irradiate a large amount of X-rays with a low energy and a large absorbed dose, and there is a problem that the exposure dose of the patient increases.
[0007]
In addition, in order to reduce the patient's exposure dose, energy subtraction technology is used, and images with different energy characteristics are copied on the upper and lower CR screens based on the intrinsic filtration of the metal plate sandwiched between the CR screens. Although a method of taking out a CR image of a screen and performing image processing has been realized, an energy subtraction image cannot be viewed in real time.
[0008]
An object of the present invention is to provide an X-ray image including a larger amount of image information, and to improve the image quality of a pulse fluoroscopic image by image processing, and an X-ray tube device suitable for the imaging device Is to provide.
[0009]
[Means for Solving the Problems]
The present invention has been made on the basis of the above-mentioned problems. A filament in which a high-vacuum is emitted is provided with a filament for emitting thermoelectrons, a focusing electrode for focusing the electrons, and an anode opposite to the filament, thereby accelerating the thermoelectrons at a high voltage. The X-ray is generated by bremsstrahlung by colliding with the anode, and by applying a bias voltage between the filament and the focusing electrode, thermionic emission from the filament is controlled by changing the electric field strength. In a grid-controlled rotary anode X-ray tube that can be used, two or more filaments for thermionic emission are shifted in the radial direction of the rotary anode, and 2 are formed on the rotary anode corresponding to each of the filaments. Electrons formed in the above-mentioned concentric circular arcs or in a plurality of curved shapes that do not overlap with each other, and at least the inner orbital plane is divided into two or more The撃軌road surface provided, connected to the independent power source for heating and a bias voltage generating circuit for each of the filaments, the bias voltages of all the filaments, the grid control rotary anode type, characterized in that a settable independently An X-ray tube is provided.
[0010]
Also, the present invention provides a high-vacuum container provided with a filament that emits thermoelectrons, a focusing electrode that focuses the electrons, and an anode that is opposed to the filament. Generates X-rays. By applying a bias voltage between the filament and the focusing electrode, thermionic emission from the filament can be controlled by changing the electric field intensity, and the anode can be rotated. and in the grid controlled rotating anode X-ray tube, perforated and capable of providing filament focus size for providing possible filament and plain radiography focus size of pulse fluoroscopy which are arranged offset in the radial direction of the rotary anode And the rotating anode is formed in concentric circular arcs corresponding to each of the filaments or in a plurality of curved shapes not overlapping each other, at least The trajectory surface located on the side is provided with an electron impact trajectory surface divided into two or more, and each filament has an electron gun connected to an independent bias voltage generation circuit so that grid control can be performed independently. A grid-controlled rotating anode type X-ray tube is provided.
[0011]
Furthermore, the present invention provides a first electron impact orbital surface having a predetermined radius and angle, and a second electron impact orbital surface in which at least one of the radius, angle or material of the first electron impact orbital surface is changed. A rotating anode formed so as to be rotatable, and the electron impact orbital surface of each rotating anode in a direction parallel to the rotation axis of the rotating anode and capable of emitting thermoelectrons toward the rotating anode. A cathode integrally provided with a plurality of filaments for emitting thermoelectrons, and a cathode disposed between the cathode and the rotating anode, and the thermoelectrons emitted from the filaments are provided. A control electrode for changing the amount of the rotary anode reaching the electron impact orbital surface corresponding to each filament, a power source for heating each filament independently, and the Has independently the control electrode of, respectively and a bias voltage circuit for supplying a bias voltage, the electronic raceway surface located on the inner circumferential side of said first and second electron impact raceway surface of the rotary anode and X-rays for pulse fluoroscopy are generated by the corresponding filaments of the cathode, and X-rays for imaging are generated by the rotating anode electron trajectory planes corresponding to the remaining filaments of the filaments. A controlled rotating anode X-ray tube is provided.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic view showing an X-ray image capturing apparatus in which the X-ray tube apparatus of the present invention is incorporated.
[0013]
As shown in FIG. 1, an X-ray imaging apparatus 1 includes an X-ray generator 11 that generates X-rays, and an X-ray, that is, an X-ray from an X-ray generator 11 that has passed through a human body O as an object to be inspected. An X-ray image intensifier tube 13 that converts an image into a visible light image, a monitor device 21 that can monitor an output image converted into a visible light image by the X-ray image intensifier tube 13, and an X-ray image for the monitor device 21 In order to display an output image converted into a visible light image by the intensifying tube 13, an imaging device 31 that captures an output image of the X-ray image intensifying tube 13 and outputs an electrical image signal is provided.
[0014]
X-rays radiated from the X-ray generator 11 pass through the human body O and are input to the input window 15 of the X-ray image intensifier tube 13 as an X-ray image. The X-ray image input to the input window 15 is enhanced by the X-ray image intensifier tube 13, converted into a visible light image by the output surface 17 of the X-ray image intensifier tube 13, and output from the output surface 17.
[0015]
The output image of the output surface 17 of the X-ray image intensifier 13 is projected onto the imaging surface of the imaging device 37 of the camera 35 by the lens 33 of the imaging device 31. The visible light image projected on the imaging surface of the imaging device 37 is converted into an image signal by the imaging device 37, subjected to predetermined image processing by the image processing device 39, and displayed on the monitor device 21.
[0016]
FIG. 2 is a schematic diagram for explaining an X-ray generation tube incorporated in the X-ray image capturing apparatus 1 shown in FIG.
As shown in FIG. 2, the X-ray generator 41 is a cathode electron gun 42 that generates thermoelectrons, and continuously accelerates the thermoelectrons generated from the cathode electron gun 42 toward the human body that is the object to be imaged. Rotating anode 43, which is a part of a motor mechanism for rotating the rotating anode 43 at a predetermined speed and rotating the rotating anode 43 at a predetermined speed, and driving the rotor 44 in a predetermined direction A stator 45 that applies force, and a vacuum envelope 46 that maintains elements other than the stator 45 in a vacuum, and the like.
[0017]
The rotating anode 43 is provided with an electron impact orbit surface 47 for photographing and electron impact orbit surfaces 48 and 49 for pulse fluoroscopy, and the thermoelectrons generated from the cathode electron gun 42 in a positional relationship as shown in FIG. It arrange | positions so that radiation | emission toward the exterior of the vacuum envelope 46 is possible. In addition, the electron impact orbital surfaces 48 and 49 for pulse fluoroscopy are formed of, for example, W (tungsten), Mo (molybdenum), Rh (rhodium), or the like.
[0018]
The cathode electron gun 42 has first and second filaments 51 a and 51 b and a third filament 52, as will be described in detail in FIG. 3, and the first and second filaments 51 a and 51 b correspond to the rotary anode 43. In combination with the electron impact orbital surfaces 48 and 49 for pulse fluoroscopy, it is used at the time of pulse fluoroscopy. The first and second filaments 51a and 51b are designed to focus on the same location as shown in FIG. Further, the cathode electron gun 42 and the filaments 51a and 51b are electrically insulated, and a predetermined bias voltage is applied between them to control the electrons incident on the rotary anode 43.
[0019]
The imaging electron impact orbit surface 47 of the rotating anode 43 is used in combination with the third filament 52 for X-ray imaging. Moreover, the electron impact orbit surfaces 48 and 49 for pulse fluoroscopy of the rotary anode 43 are formed at different angles, and the first and second filaments are focused to provide different effective focal lengths. Note that the materials of the two pulse fluoroscopic electron impact track surfaces 48 and 49 may be changed as necessary. That is, the above-described W, Mo, or Rh may be used in any combination.
[0020]
FIG. 4 is a block diagram schematically showing a control system of the X-ray image capturing apparatus 1 shown in FIG.
As shown in FIG. 4, the first and second filaments 51 a and 51 b of the cathode electron gun 42 of the X-ray generator 11 are connected to a heating power source 60.
[0021]
The cathode electron gun 42 also serving as a grid electrode is connected to a bias power supply circuit 62 connected to a pulse generation circuit 61. The bias power supply circuit 62 is formed such that the grid bias voltage can be arbitrarily changed from 0 V to several thousands V within a time of 1 millisecond or less. In addition, since the bias power supply circuit 62 is installed independently for each filament, even if one filament is disconnected, if the controller detects this and disconnects the system, it remains. The filament can be used continuously and can provide fail-safety.
[0022]
The pulse generating circuit 61 is supplied with fluoroscopic pulses P1 and P2 that are reduced to a predetermined frequency by the basic clock generating circuit 63 and the frequency dividing circuit 64. Normally, the fluoroscopic pulses P1 and P2 are set at the same interval, that is, at the same frequency, and the timing at which each is generated is shifted by 1/2 pulse. That is, as will be described below with reference to FIGS. 5 (a) and 5 (b), when one pulse is on, the other pulse is off, and substantially the first and second filaments 51a and 51b It is set to drive each one alternately. The bias power supply circuit 62 rotates the thermoelectrons for fluoroscopic X-rays from the corresponding filament by reducing the bias voltage output applied for a predetermined period each time the pulses P1 and P2 are supplied. It is possible to reach the electron impact orbit surfaces 48 and 49 for pulse fluoroscopy of the anode 43. As a result, fluoroscopic X-rays are emitted to the outside of the X-ray generator 41.
[0023]
When fluoroscopic X-rays are emitted, an X-ray image formed on the imaging element 37 by the camera 35 of the imaging device 31 is displayed on the monitor device 21.
Referring again to FIG. 4, the third filament 52 of the cathode electron gun 42 of the X-ray generator 11, a bias power supply that photographing switch (not shown) provided in the vicinity of the monitor device 21 is turned on as a trigger The bias voltage output applied from the circuit 65 is lowered for a predetermined period, so that the thermal electrons for the X-ray for imaging from the third filament 52 can reach the imaging electron impact orbit surface 47 of the rotary anode 43. An X-ray image is taken by X-rays radiated outward from the shooting electron impact orbital surface 47. The bias power supply circuit 65 is formed such that the grid bias voltage can be arbitrarily changed from 0 V to several thousands V within a time of 1 millisecond or less. At the time of this photographing, the image capturing by the image capturing device 31 and the display of the image on the monitor device 21 are stopped.
[0024]
Hereinafter, an example of the operation of the X-ray imaging apparatus shown in FIGS. 1 to 5 will be described.
The timing at which the first filament 51a outputs thermoelectrons for fluoroscopic X-ray is set to the rotation cycle of the deep orbital surface 49 of the rotary anode 43, and the second filament 51b is heated for fluoroscopic X-ray. If the bias control shown in FIG. 5, that is, the grid voltage control, is performed in accordance with the rotation period of the orbital surface 48 having a shallow angle according to the timing of outputting electrons, the first filament 51a has a large focal point and the second filament 51b. With this, small focal points can be alternately imaged. It is also possible to make the same focus. In this case, the thermoelectrons from the filaments 51a and 51b are accelerated toward the first and second orbital surfaces 47 and 48 of the electron focusing electrode, and generate X-rays by braking radiation when they collide with the anode. This is well known.
[0025]
In addition, if it is possible to change the tube voltage when thermoelectrons are generated by the first filament 51a and when thermoelectrons are generated by the second filament 51b, images with different energies are collected alternately. It becomes possible.
[0026]
In any case, the image capturing system collects images in synchronization with a synchronization signal output every rotation of the rotating anode 43. In the case of moving from pulse fluoroscopy to imaging, the generation timing of X-rays for pulse fluoroscopy changes according to the connection of the power source to the third filament 52, that is, the start of heating of the filament and the rotation of the electron focusing electrode. Since it is difficult to collect the subtraction video, the image processing is stopped. In this case, there is no problem if the shadow of the image shadow agent can be seen. Therefore, it is desirable to switch both the first and second filaments 51a and 51b to a small focal point.
[0027]
On the other hand, at the time of photographing, the X latent image is obtained by setting the grid bias to 0 at a predetermined timing following the heating of the third filament 52, the application of the grid bias voltage, and the rotation of the electron focusing electrode. Taken.
[0028]
As described above, when used in a medical X-ray tube apparatus, an image with many high-frequency components due to a small focal point, an image with many low-frequency components due to a large focal point, and an image with high energy components due to differences in target materials, low energy Images by components can be collected in a predetermined order. These images are added and subtracted from high-frequency emphasis and low-frequency emphasis images, and addition of X-rays having many high energy components and X-rays having many low energy components. More advanced images such as elimination of obstructive bones or organ shadows, seeding shadows of cancer lesions, enhancement of microcalcium images, and enhancement of catheter shadows for intravascular catheter treatment by subtraction (energy subtraction) Image information that can be processed can be collected in real time.
[0029]
In addition, when switching from pulse fluoroscopy to film photography in angiography using contrast medium, the focus speed for simple imaging is controlled by the grid, so that the anode rotation speed of the electron focusing electrode is changed from low speed to high speed before the contrast medium is added. Simultaneously with the start-up, the main heating of the filament for simple imaging can be performed while maintaining a high voltage, the heating start time of the filament is shortened, and the imaging timing at the moment when the contrast agent flows is not missed.
[0030]
In the above-mentioned X-ray generator, the attachment positions of at least two thermionic emission filaments with respect to the anode are shifted from each other in the radial direction of the electron focusing electrode, and different electron impact trajectories according to the individual filaments. Arbitrary X-rays can be obtained by forming a surface or changing the angle of the electron impact track surface for each track surface. In addition, when the use of characteristic X-rays is effective, the material of the raceway surface can be changed.
[0031]
Further, a part of the electron impact raceway surface, in particular, the inner raceway surface can be divided into two or more, and the angle can be changed for each divided position, and if necessary, the material can be changed.
[0032]
Furthermore, the rotational position of the anode is detected by an optical, magnetic or electrical method, the grid bias voltage of the electron gun is controlled in synchronization with the rotation of the anode, and the location of the electron impact orbital surface of the electron focusing electrode is controlled. It is also possible to change the length dimension of the focal point by selecting different angles.
[0033]
Furthermore, the width dimension can be controlled by applying a weak grid bias voltage, and two or more focal dimensions can be created by changing the angle of the track surface and the grid bias voltage with the same filament.
[0034]
【The invention's effect】
As described above, the X-ray tube apparatus of the present invention is different in the line quality and the focal size by controlling the arbitrary grid bias voltage synchronized with the rotation of the anode and the angle and material of the orbital plane. X-rays can be generated while switching at high speed.
[0035]
The X-ray image thus obtained is captured as a digital image by an X-ray image intensifier tube and a CCD camera, and subtraction and the like are performed by using a high-frequency component and a low-frequency component of the image information, an image with high energy X-rays, and an image with low X-rays By performing image processing, it is possible to remove more obtrusive bones or organ shadows, to increase the shadow of seeds in cancerous lesions, to enhance microcalcium images, and to enhance catheter shadows in the case of intravascular catheter treatment. Collection of image information capable of image processing is possible in real time, and a higher quality diagnostic image can be obtained.
[0036]
In angiography using a contrast agent, when switching from pulse fluoroscopy to film imaging, the focus of the simple imaging is controlled by grid control, so that the anode rotation speed of the electron focusing electrode is changed from low to high before the contrast agent is introduced. Simultaneously with the start to rotation, the main heating of the filament for simple imaging is possible, the heating start time of the filament is shortened, and the missed imaging timing at the moment when the contrast agent flows can be reduced.
[0037]
Furthermore, the filament for pulse fluoroscopy can be provided with two filaments of the same structure if it has a V-groove type electron focusing electrode structure, as is often seen in an electron gun of a conventional X-ray tube. Either filament can form two types of focal dimensions. In this case, it is possible to extend the life of the filament by using the left and right alternately, or to continue using at one focal point even if one is broken.
[0038]
Since the grid bias power supply is independent, even if one filament breaks and contacts the electron focusing electrode, if the system detects this and disconnects the system, the remaining focus can be controlled by the grid. And can provide fail-safety.
Thereby, it is possible to reduce the time and amount of X-ray energy applied to the affected part of the human body that is the imaging target, and to protect the patient from X-ray exposure.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an X-ray imaging apparatus incorporating an X-ray generation tube according to an embodiment of the present invention.
FIG. 2 is a schematic diagram illustrating an X-ray generator tube incorporated in the X-ray image capturing apparatus shown in FIG.
3 is a schematic diagram showing a relative positional relationship between an electron focusing electrode and a cathode electron gun of the X-ray generation tube shown in FIG. 2;
4 is a block diagram schematically showing a control system of the X-ray imaging apparatus shown in FIG. 1. FIG.
5 is a timing chart showing bias voltage control timing for causing the output of each filament of the X-ray generator tube shown in FIG. 2 to reach the electron focusing electrode. FIG.
[Explanation of symbols]
1 ... X-ray imaging device,
11 ... X-ray generator,
13 ... X-ray image intensifier tube,
21 ... monitor device,
31 ... imaging device,
42 ... cathode electron gun,
43 ... Electron focusing electrode,
47 ... Electronic impact surface for shooting,
48 ... Electron impact orbital surface for pulse fluoroscopy,
49… Electron impact orbital surface for pulse fluoroscopy,
51a ... first filament,
51b ... second filament,
52 ... the third filament,
60 ... power supply for heating,
61 ... pulse generation circuit,
62… Bias power supply circuit,
65: Bias power supply circuit.

Claims (4)

A high-vacuum container is provided with a filament that emits thermoelectrons, a focusing electrode that focuses the electrons, and an anode facing the filament. The thermoelectrons are accelerated at a high voltage to collide with the anode, and X-rays are generated by bremsstrahlung. In a grid-controlled rotary anode X-ray tube that can control thermionic emission from the filament by changing the electric field strength by applying a bias voltage between the filament and the focusing electrode,
Two or more filaments for thermionic emission are displaced in the radial direction of the rotating anode, and two or more concentric arcs formed on the rotating anode corresponding to each of the filaments or a plurality that do not overlap each other. An electron impact raceway surface that is formed in the shape of a curved line and is divided into two or more at least on the raceway surface located inside, and a heating power source and a bias voltage generation circuit are connected independently for each filament, A grid-controlled rotary anode X-ray tube characterized in that the filament bias voltage can be set independently.   The grid-controlled rotating anode X-ray tube according to claim 1, wherein the filament can provide two or more focal dimensions. A high-vacuum container is provided with a filament that emits thermoelectrons, a focusing electrode that focuses the electrons, and an anode facing the filament. The thermoelectrons are accelerated at a high voltage to collide with the anode, and X-rays are generated by bremsstrahlung. be one, by applying a bias voltage between said focusing electrode and said filament, a controllable thermionic emission from the filament a change in electric field strength, rotatable with the grid controlled anode In rotating anode type X-ray tube,
The filament has a filament capable of providing a focal dimension for pulse fluoroscopy and a filament capable of providing a focal dimension for simple imaging, which are arranged offset in the radial direction of the rotary anode, and corresponds to each of the filaments on the rotary anode. Concentric circular arcs formed as above or a plurality of curved shapes that do not overlap each other, and at least the inner orbital plane is provided with an electron impact orbital plane that is divided into two or more, and each filament is A grid-controlled rotating anode type X-ray tube comprising an electron gun connected to an independent bias voltage generating circuit capable of independent grid control. A first electron impact orbital surface having a predetermined radius and angle is integrally formed with a second electron impact orbital surface in which at least one of the radius, angle or material of the first electron impact orbital surface is changed. A rotating anode formed rotatably, and
A plurality of thermoelectrons can be emitted toward the rotating anode and provided independently to each of the electron impact orbital surfaces of the rotating anode in a direction parallel to the rotation axis of the rotating anode. A cathode integrally having a filament of
A control electrode provided between the cathode and the rotating anode and changing the amount of thermionic electrons emitted from the respective filaments reaching the electron impact orbital plane corresponding to the respective filaments of the rotating anode;
A power source for independently heating each of the filaments;
A bias voltage circuit for independently supplying a bias voltage to each of the control electrodes;
Have
X-rays for pulse fluoroscopy are generated by the cathode filament corresponding to the electron orbital surface located on the inner peripheral side of the first and second electron impact orbital surfaces of the rotating anode, A grid-controlled rotary anode X-ray tube characterized in that X-rays for imaging are generated by a rotary anode electron orbit plane corresponding to the remaining filaments in the inside.

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